Pope, Hamish1 and Zalok, Ehab2
1 PhD Candidate, Carleton University, 1125 Colonel By Dr, Ottawa, ON, Canada, HamishPope@cmail.carleton.ca
2 Associate Professor, Carleton University, 1125 Colonel By Dr, Ottawa, ON, Canada, EhabZalok@cunet.carleton.ca
ABSTRACT
Masonry elements have long been known to possess excellent fire protection qualities. Masonry is well suited as a fire barrier because it works effectively to isolate and contain fire, heat, and smoke. Masonry is also able to keep its strength and resist collapse when put under a fire load. For these reasons, masonry is commonly used as a fire barrier in buildings. While masonry does have several positive attributes when exposed to fire, there are some issues that occur when masonry is heated, other than simple loss of strength. One common issue is concrete spalling (pieces of the concrete falling off or violently exploding). The second common issue is thermal bowing (when the wall bends during fire exposure). These issues can have an impact on the fire resistance rating of the member, so it is important to know why they happen and how to mitigate their effects. This paper discusses how concrete masonry behaves when it is heated and how its various properties change with higher temperatures. The effect of these property changes is described, and recommendations are made. An explanation on how spalling and thermal bowing occur is given, and the damage they cause during and after the masonry walls are heated is described. Methods of reducing the likelihood of these two major issues occurring in masonry are discussed.
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